The invention relates to the preservation of substances in a container, and in particular to the preservation of the liquidity of paint, varnish, lacquer, shellac and the like in cylindrical containers.
Paint, varnish, shellac and a great many other liquids are conventionally packaged in containers having bases and upstanding walls, these containers commonly being in the form of cylindrical metal cans. The containers are provided with covers or lids for preventing spillage, contamination of the liquid, and in the case of liquids of the type to which this invention has particular applicability, for preventing the drying of the liquid to form a skin thereon. (In the discussion to follow, reference shall be made to the preservation of the liquidity of paint, but the reference to paint should be understood to extend to any liquid having a tendency to dry to an extent to form a hardened surface or skin on the liquid, as well as to particulate solids such as coffee which deteriorate when exposed to ambient air). The paint containers are usually provided with a rim configured to engage the correspondingly configured lip of the lid to seal--preferably hermetically--to prevent the flow of air across the paint and the concomitant drying of the surface of the paint due to the evaporation of moisture therefrom. It is well known, however, that even though a fresh can of paint generally preserves the liquidity thereof, once opened the seal of the lid on the can cannot be re-established to prevent the drying of the paint. Moreover, it is not an infrequent occurence that the lid of a partially used can of paint is either mislaid or so badly bent that it cannot be reaffixed to the container, in which case the entire unused portion of the paint is likely to become dried out and unusable.
Prior proposals for preserving paint have not been adopted, and those proposals are either impracticable or uneconomical. Various patents have issued disclosing devices having components for engaging the surface of paint or the like in a container to prevent the drying of the liquid, and in some instances peripheral skirts engaging the inner surface of the containers block the passage of air to the surface of the liquid. Such patents include U.S. Pat. Nos. 1,092,902, 2,453,274, 2,465,755, 2,566,195, 2,609,119, 2,616,590, 3,049,261, 3,129,842, 3,266,662, and 3,784,051. The devices described in the preceding patents all have a plurality of components, and none of them have means for evacuating air once the device is seated on the liquid to be preserved. U.S. Pat. Nos. 1,936,857 and 3,578,478 disclose complex devices for preserving coffee; the former of these patents includes a bulb for evacuating air from the coffee, but this is not done to enhance the sealing effect of the device on the coffee. U.S. Pat. No. 890,196 describes a tobacco package having a sponge held in place over the tobacco by a spring biassed cup to keep the tobacco moist. A lid for hermetically sealing a container such as an ice cube tray is the subject of U.S. Pat. No. 3,164,289. The foregoing patents thus relate to complicated devices for preserving various liquids or solids, and they have not found acceptance in the marketplace.
The invention in its preferred form is a unitary device including a circular central portion having an upstanding, resilient, compressible handle, a downwardly extending channel extending around the central portion, radially ribs extending across the channel, and a peripheral flange for engaging the walls of the container. The cover folds along the ribs upon compression of the handle to enable the insertion and removal of the device into and out of a container.